江淮入梅的年际变化及其与北大西洋涛动和海温异常的联系

INTERANNUAL VARIABILITY OF THE MEIYU ONSET AND ITS ASSOCIATION WITH NORTH ATLANTIC OSCILLATION AND SSTA OVER NORTH ATLATIC

文中首先采用简单相关和合成分析的方法研究了江淮入梅的年际变化与前期冬季环流和前期冬、春全球海温的关系。研究结果表明江淮入梅的早晚与前期冬季北半球大型环流存在显著的相关 :入梅早的年份 ,其前期冬季北大西洋涛动强 ,北半球只有一个强的极涡并位于格陵兰上空 ,东亚大槽弱 ;入梅晚的年份 ,则其前期冬季环流表现为 ,北大西洋涛动弱 ,北半球存在两个极涡 ,其中一个仍然位于格陵兰上空 ,而另一个则位于西伯利亚上空 ,东亚大槽较常年强。江淮入梅的年际变化与前期冬春北大西洋海温的相关分析表明 :入梅早的年份 ,北大西洋海温较常年偏暖 ;入梅晚的年份 ,前期冬春北大西洋海温较常年偏冷。文中还用 CCM3模拟了冬、春季北大西洋海温增暖对后期江淮入梅和梅雨期降水的影响 。

In the context of simple correlation and composite analysis ,study is performed of the correlation between Meiyu onset dates(MOD) and atmospheric circulation in the previous winter. Result shows that the MOD is significantly related to the atmospheric features in the previous winter with strong North Atlantic Oscillation(NAO) for early Meiyu onset and v.v.. Result also indicates that there exists pronounced correlation between the MOD and SST over the North Atlantic in the previous winter-to-spring with positive SST anomalies for early Meiyu onset and negative anomalies for late Meiyu onset , which implies important significance for Meiyu onset prediction. Finally, numerical simulation is taken to investigate the mechanism of effects on the Meiyu onset and precipitation of the warm sea surface temperature over the North Atlantic.